In early Buddhist scriptures, the word arahant refers to an enlightened being. A Buddha, in the most common usage, is an arahant who has discovered the path to enlightenment without learning about it from someone else.
In the early scriptures and in modern Theravada Buddhism, it means anyone who has reached the total Awakening and attained Nibbana, including the Buddha. Arahant is a person who has destroyed greed, hatred and delusion, the unwholesome roots which underlie all fetters. Who upon decease will not be reborn in any world, having wholly cut off all fetters that bind a person to the samsara. In the Pali Canon, the word is sometimes used as a synonym for tathagata.
After attainment of Nibbana, the five aggregates (physical forms, feelings/sensations, perception, mental formations and consciousness) will continue to function, sustained by physical bodily vitality. This attainment is termed the nibbana element with a residue remaining. But once the Arahant pass-away and with the disintegration of the physical body, the five aggregates will cease to function, hence ending all traces of existence in the phenomenal world and thus total release from the misery of samsara. It would then be termed the nibbana element without residue remaining. Parinibbana occurs at the death of an Arahant.
These three awakened beings are classified as Arahant:
1. Sammasambuddha, usually just called Buddha, who discovers the truth by himself and teaches the path to awakening to others.
2. Paccekabuddha, who discovers the truth by himself but lacks the skill to teach others.
3. Savakabuddha, who receive the truth directly or indirectly from a Sammasambuddha.
The exact interpretation and etymology of words such as Arahatto (Pali) and Arhat (Sanskrit) remains disputed. Research gathered together circa 1915 and published in the PTS dictionary interpret the word as meaning "the worthy one" in Theravada tradition. This has been challenged by more recent research, resulting from the etymological comparison of Pali and early Jain Prakrit forms (arihanta and arahanta). The latter challenges the assumption that the root of the word is Pali araha; Richard Gombrich has proposed an etymology of ari + hanta, bringing the root meaning closer to Jina (an epithet commonly used of both the the leaders of the Jain religion and Buddha).